<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>无参函数</title>
</head>
<body>
    <script>
        // 求圆的面积
        function getCirArea(){
            var r = 2;
            var s = Math.PI*r*r;
            console.log(s.toFixed(2));
        }
        getCirArea()
    </script>
</body>
</html>